Photovoltaic (PV) power systems frequently track the sun to various degrees to increase an amount of energy produced by the system. These trackers typically move photovoltaic modules to adjust an angle of incidence of the sunlight on the surface of the PV modules. In particular, trackers typically rotate the PV modules around an axis principally oriented north to south, tilting the modules to as much as 60 degrees towards the east and west and adjusting tilt within this range throughout the day. By tracking the position of the sun, PV power systems often produce 20-30% more energy than fixed-tilt systems.
A common configuration of horizontal single-axis trackers (“SAT”) as described above includes a single actuator near the center of a row of PV modules, potentially with 80-120 modules tilted by a single actuator. The angle of tilt is defined by the position of the actuator, while a torque tube or other similar device transfers moments and positions the rest of the row at this tilt. However, environmental loading (wind, snow, dead load, etc.) can twist portions of a row away from the intended tilt angle. This effect requires design considerations that add cost in order to decrease risk of failures.
To reduce row twist, some PV systems may have shorter row lengths or more than one actuator per row. These approaches can reduce the risk of system failure from excessive row twist, but may increase the PV system cost as well as overhead and maintenance costs. Furthermore, when multiple actuators are used, the actuators within a row must communicate such that, for example, other actuators stop moving if one actuator fails. This communication can be by electronic, mechanical, or other means. However, this active control brings additional failure modes that must be considered in the design of the PV system.
The figures depict various embodiments of this disclosure for purposes of illustration only. One skilled in the art can readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein can be employed without departing from the principles of the invention described herein.